Parallel scanning of wireless channels

ABSTRACT

Methods, systems, and apparatus for parallel scanning of channels in communication networks are described herein. A parallel scanning device performs a scanning operation that includes parallel (i.e., simultaneous) scanning of channels that are in a common frequency band or in different frequency bands. The parallel scanning of channels results in a reduction of scan time, which reduces power consumption. Furthermore, a scanning operation may undesirably interrupt and/or delay normal communication traffic to and from the parallel scanning device, and the comparatively shorter scan time resulting from the parallel scanning operation can reduce such interruption and/or delay.

CROSS-REFERENCE TO RELATED APPLICATION(S)

This application claims the benefit of U.S. Provision Application No.61/838,518, filed on Jun. 24, 2013, which is incorporated by referenceherein in its entirety.

BACKGROUND

1. Technical Field

The subject matter described herein generally relates to methods andapparatuses for parallel scanning of channels in communication networks,such as a wireless local area network (WLAN).

2. Description of Related Art

Communication systems typically support wired and wirelesscommunications between communication devices. Communication systemsoperate in accordance with one or more communication standards, such asEthernet or IEEE 802.11/Wi-Fi. Depending on the type of communicationsystem, a wireless communication device, such as a cellular telephone orlaptop computer, may communicate directly or indirectly with otherwireless communication devices. For direct communication (i.e.,point-to-point), the participating wireless communication devices tunetheir transceivers to the same channel(s) (e.g., one of a variety ofchannels in an operating frequency range of the wireless communicationsystem) and communicate over those channel(s). For indirectcommunication, each wireless communication device communicates directlywith an associated access point via an assigned channel.

Thus, for indirect wireless communication, a wireless communicationdevice typically performs a scanning operation to discover access pointsthat are available to communicate with the wireless communicationdevice. Conventionally, the scanning operation includes sending a proberequest and listening for probe request response(s) from availableaccess points in a sequential manner, scanning one channel at a timeuntil all channels have been scanned for a particular frequency band.The scanning operation may continue with respect to another frequencyband if the wireless device is capable of operating in that frequencyband. The length of the scanning operation depends on the number ofchannels and/or frequency bands that are to be scanned. The longer thescanning operation, the more power is consumed. Many wirelesscommunication devices are mobile devices that are battery-powered. Thus,power conservation (e.g., powering down transceivers) is important,especially for wireless communication devices.

BRIEF SUMMARY

Methods, systems, and apparatuses are described for parallel scanning ofwireless channels in a communication network, substantially as shown inand/or described herein in connection with at least one of the figures,as set forth more completely in the claims.

BRIEF DESCRIPTION OF THE DRAWINGS/FIGURES

The accompanying drawings, which are incorporated herein and form a partof the specification, illustrate the subject matter of the presentapplication and, together with the description, further serve to explainthe principles of the embodiments described herein and to enable aperson skilled in the pertinent art to make and use such embodiments.

FIG. 1 is a block diagram of an example simultaneous dual-bandcommunication system in accordance with an embodiment.

FIG. 2 is a block diagram of an example parallel scanning device shownin FIG. 1 in accordance with an embodiment.

FIG. 3 depicts a flowchart of an example method for parallel scanning inaccordance with an embodiment.

FIG. 4 depicts a timing diagram of an example parallel scanningtechnique in accordance with an embodiment.

FIG. 5 is a block diagram of another example parallel scanning device inaccordance with an embodiment.

FIG. 6 depicts a flowchart of an example method for scanning a pluralityof channels in a wireless network frequency band in accordance with anembodiment.

FIG. 7 is a block diagram of an example computing system that may beused to implement various embodiments.

The subject matter of the present application will now be described withreference to the accompanying drawings. In the drawings, like referencenumbers indicate identical or functionally similar elements.Additionally, the left-most digit(s) of a reference number identifiesthe drawing in which the reference number first appears.

DETAILED DESCRIPTION A. Introduction

The following detailed description discloses numerous exampleembodiments. The scope of the present patent application is not limitedto the disclosed embodiments, but also encompasses combinations of thedisclosed embodiments, as well as modifications to the disclosedembodiments.

References in the specification to “one embodiment,” “an embodiment,”“an example embodiment,” etc., indicate that the embodiment describedmay include a particular feature, structure, or characteristic, butevery embodiment may not necessarily include the particular feature,structure, or characteristic. Moreover, such phrases are not necessarilyreferring to the same embodiment. Furthermore, when a particularfeature, structure, or characteristic is described in connection with anembodiment, it is submitted that it is within the knowledge of oneskilled in the art to affect such feature, structure, or characteristicin connection with other embodiments whether or not explicitlydescribed.

Methods, systems, and apparatuses for parallel scanning of channels incommunication networks are described herein. In accordance with certainembodiments, a parallel scanning device performs a scanning operationthat includes parallel (i.e., simultaneous) scanning of channels thatare in a common (i.e., same) frequency band or different frequencybands. The parallel scanning of channels may result in a reduction ofscan time, which may reduce power consumption. For instance,transceivers in the parallel scanning device may be powered down orplaced in an idle mode after the scanning operation is completed. Thepower consumed during idle mode may be less than the power consumedduring normal operating mode. Furthermore, the scanning operation mayundesirably interrupt and/or delay normal communication traffic to andfrom the parallel scanning device, and a shorter scan time can reduce(e.g., eliminate) this interruption and/or delay.

Numerous exemplary embodiments are described as follows. It is notedthat any section/subsection headings provided herein are not intended tobe limiting. Embodiments are described throughout this document, and anytype of embodiment may be included under any section/subsection.Furthermore, disclosed embodiments may be combined with each other inany manner.

B. Example Embodiments

FIG. 1 is a block diagram of an example simultaneous dual-bandcommunication system 100 in accordance with an embodiment. Communicationsystem 100 supports wireless and wired communications between wirelessand/or wired devices, such as one or more access point(s) 102, aparallel scanning device 104, a camcorder 108, a camera 110, a printer112, one or more speakers 114, a cellular phone 116, an external harddrive 118, and a monitor 120. Parallel scanning device 104 is adual-radio/transceiver device (e.g., station) that is capable ofscanning WLAN channels, in one or more frequency bands, in parallel(i.e., scanning multiple (e.g., two) channels by simultaneously sendingprobe requests via the multiple channels). Parallel scanning device 104may be a wired or wireless device. Each of the devices in communicationsystem 100 may be directly or indirectly connected to a communicationnetwork 106 via a wired or a wireless connection. Communication amongthe devices of communication system 100 is carried out overcommunication network 106 using well-known network communicationprotocols. Communication network 106 may be a wide-area network (e.g.,the Internet), a local area network (LAN) such as a wireless LAN (WLAN),a public switch telephone network, another type of network, or acombination thereof. In addition, access point(s) 102 may communicatewith each other and/or other devices not shown in FIG. 1 directly orindirectly via a system controller, the public switch telephone network,the Internet, and/or via some other wide area network.

Communication system 100 may operate in accordance with one or morewired communication standards (e.g., Ethernet, System Packet Interface(SPI), or Secure Digital Input Output (SDIO)), wireless communicationstandards (e.g., Institute of Electrical and Electronics Engineers(IEEE) 802.11, Bluetooth, advanced mobile phone services (AMPS), digitalAMPS, global system for mobile communications (GSM), code divisionmultiple access (CDMA), time division synchronous code division multipleaccess (TD-SCDMA), local multi-point distribution systems (LMDS), ormulti-channel-multiple-point distribution systems (MMDS)), or variousother standards.

For illustration purposes, embodiments may be described in connectionwith the IEEE 802.11/Wi-Fi standards, which implement WLAN communicationin the 2.4, 3.6, 5, and 60 gigahertz (GHz) frequency bands. Althoughembodiments are described below with respect to the 2.4 and 5 GHzfrequency bands, it will be recognized that the example embodiments areapplicable to other suitable frequency bands. Components thatcommunicate via a wireless medium in a WLAN are referred to as stations(STAs), which are equipped with wireless network interface controllers.Stations may act as access points or clients. An access point (e.g., arouter) is a base station in a wireless network. Such a base stationtransmits and receives radio signals to enable communication amongwireless clients. Wireless clients include but are not limited to mobiledevices (e.g., laptops, personal digital assistants (PDAs), smartphones,and desktops/workstations that are equipped with a wireless networkinterface).

In order to participate in wireless communication, parallel scanningdevice 104 may perform a parallel scanning operation to find a suitablefirst access point (e.g., one of access point(s) 102), and thenauthenticate and associate with the first access point. As parallelscanning device 104 moves (e.g., out of range of the first accesspoint), it may authenticate a second access point (e.g., one of accesspoint(s) 102 that is different from the first access point). Whenassociation with the first access point is no longer desirable, parallelscanning device 104 may associate with the second access point. Thesecond access point notifies the first access point of the new locationof parallel scanning device 104 and terminates the previous associationof parallel scanning device 104 with the first access point. At somepoint, parallel scanning device 104 may need to perform another scanningoperation to find another access point and repeat the authentication andassociation process.

FIG. 2 is a block diagram of an example parallel scanning device 200configured for parallel scanning in accordance with an exampleembodiment. Parallel scanning device 200 may be an example of parallelscanning device 104 shown in FIG. 1. Parallel scanning device 200includes a scanner 202, a first transceiver 206, and a secondtransceiver 210. First transceiver 206 and second transceiver 210 areshown in FIG. 2 as being coupled to respective antennas 208 and 212 forillustrative purposes, though it will be recognized that firsttransceiver 206 and second transceiver 210 may be coupled to a common(e.g., single) antenna. In some example embodiments, first antenna 208and second antenna 212 are included in an antenna array.

In telecommunications, relatively low-frequency parts of a signal thatis to be transmitted may be converted to relatively higher frequenciesfor transmission purposes because the relatively lower frequencies maybe passed with greater distortion in some communication media. Theoriginal, relatively low-frequency components of the signal are commonlyreferred to as the baseband signal and the converted, relativelyhigh-frequency components are commonly referred to as the radiofrequency (RF) signal. A transceiver may be referred to herein as aradio, a radio transceiver, and/or a transceiver chain as eachtransceiver operates under the medium access control (MAC) specificationand the physical layer (PHY) specification.

Parallel scanning device 200 is operable in different modes. Forexample, parallel scanning device 200 may be operated in a single-inputsingle-output (SISO) mode, in which one transmitter and one receiver areutilized to send data over a single radio frequency channel;multiple-input multiple-output mode, in which two or more transmittersand two or more receivers are utilized to send data simultaneously overthe same radio frequency channel, or real simultaneous dual-band (RSDB)mode, in which multiple transceivers are utilized to send datasimultaneously over the same or different radio frequencychannels/bands. The input and output terminology refers to the radiofrequency channel. For example, the input (single or multiple) is drivenby the transmitter(s) and the output (single or multiple) feeds thereceiver(s).

Scanner 202 is configured to conduct a scanning operation to discoveraccess points that are available to communicate with the parallelscanning device 200 via a wireless medium. Each of first transceiver 206and second transceiver 210 may include a data modulation stage and aradio frequency (RF) stage. The data modulation stage, in the basebandprocess, converts between data and baseband signals in accordance with aparticular wireless communication standard (e.g., 802.11 standards). TheRF stage includes transmitter circuitry and receiver circuitry, andconverts between baseband signals and RF signals. The RF stage mayconvert directly between baseband and RF or may include one or moreintermediate frequency stages. Each of first transceiver 206 and secondtransceiver 210 may be associated with an antenna configuration inaccordance with an operating mode (e.g., SISO, MIMO, RSDB) thereof. Anantenna configuration indicates a relationship between first antenna 208and second antenna 212 (e.g., same or different) and how they may beassociated with first transceiver 206 and second transceiver 210. Eachof scanner 202, first transceiver 206, and second transceiver 210 may beimplemented in hardware, or a combination of hardware and softwareand/or firmware. The operation of parallel scanning device 200 will bedescribed below.

Scanner 202 is configured to perform a scanning operation on channelsthat are included in one or more frequency bands (e.g., 2.4 GHz or 5GHz) to discover access point(s) that are available to communicate withparallel scanning device 200. In accordance with the scanning operation,scanner 202 provides probe requests that are to be transmitted by firsttransceiver 206 and/or second transceiver 210 and listens for proberesponses from available access points that are received by firsttransceiver 206 and/or second transceiver 210. Scanner 202 includesscanning logic 204, which is configured to provide a scan instructionindicating that multiple channels of a wireless network are to bescanned simultaneously. For example, scanning logic 204 is configured toprovide a scan instruction to first transceiver 206 and secondtransceiver 210, upon determining that a scanning operation is to beperformed, instructing first transceiver 206 and second transceiver 210to prepare for and conduct a parallel scan operation. The scanningoperation may include sending a frame to an access point with which theparallel scanning device 200 is currently associated, informing theaccess point that parallel scanning device 200 is going into power-savemode. In the power-save mode, parallel scanning device 200 sends proberequests and may receive probe responses in return.

As part of the scanning operation, scanning logic 206 may determinewhich channel to start scanning and/or which frequency band(s) to assignto first transceiver 206 and/or second transceiver 210. For example, the2.4 GHz frequency band covers the frequency range of 2.4 to 2.4835 GHzand may include channels 1-14, for example. The 5 GHz frequency bandcovers the frequency range of 5.15 to 5.35 and 5.725 to 5.825 GHz andincludes far more channels than the 2.4 GHz frequency band. In either ofthese frequency bands, the number of channels in each frequency banddepends on the geographic region (e.g., country) in which parallelscanning device 200 operates because the usage of frequency bandstypically is regulated by governmental entities. For example, in theUnited States, the 2.4 GHz frequency band includes 11 channels, and the5 GHz frequency band includes 22 channels. In Europe, the 2.4 GHzfrequency band includes 13 channels, and the 5 GHz frequency bandincludes 24 channels. In Japan, the 2.4 GHz frequency band includes 14channels, and the 5 GHz frequency band includes 27 channels.

Scanning logic 204 is further configured to determine an antennaconfiguration and/or to configure antennas that are available to firsttransceiver 206 and second transceiver 210 (e.g., antenna 208 and/orantenna 212). The antenna configuration may influence the scanningoperation. In an example embodiment, first transceiver 206 and secondtransceiver 210 share a common (i.e., same) antenna (e.g., antenna 208or antenna 212) and may simultaneously send a first probe request and asecond probe request from the common antenna. In accordance with thisembodiment, a parallel scan may be performed with respect to channels indifferent frequency bands or with respect to channels in a commonfrequency band so long as the channels that are simultaneously scannedare sufficiently separated so that the scanning of each channel does notunduly interfere with scanning of the other channel. In another exampleembodiment, each of first transceiver 206 and second transceiver 210 hasa dedicated antenna. For instance, as shown in FIG. 2, first transceiver206 may be coupled to first antenna 208, and second transceiver 210 maybe coupled to second antenna 212. In accordance with this embodiment,scanning logic 204 may simultaneously provide a first probe request anda second probe request from the first antenna 208 and second antenna212, respectively. In further accordance with this embodiment, aparallel scan may be performed with respect to channels in differentfrequency bands or with respect to channels in a common frequency band.

If parallel scanning device 200 is currently associated with an accesspoint, scanning logic 204 may send the associated access point a message(e.g., frame) indicating that parallel scanning device 200 intends to gointo power-save mode. During power-save mode, normal traffic between theassociated access point and parallel scanning device 200 may betemporarily suspended (e.g., the associated access point may hold (e.g.,buffer) incoming data and hold outgoing data) until parallel scanningdevice 200 is no longer in power-save mode. Typically, in order tomaintain the association between parallel scanning device 200 and theassociated access point, parallel scanning device 200 needs to be activeon the channel of the associated access point (e.g., home channel) atpredetermined times (e.g., according to beacon timing controlled by theassociated access point) to receive a beacon from the associated accesspoint. A beacon is a frame that includes information such as timestamp,beacon interval, capability, service set identifier, supported rates,country, power constraint, channel switch announcement, antenna,high-throughput capabilities, and other parameters or information. Whenan association needs to be maintained, the scanning operation may attimes be suspended to accommodate the receipt of the beacon on the homechannel. Depending on the operating mode of parallel scanning device200, it may be possible for only one transceiver to utilize the homechannel to await the beacon while the other transceiver may continuewith the scanning process. When parallel scanning device 200 is notcurrently associated with an access point, the scanning operation may beperformed through completion (i.e., all channels in all frequency bandshave been scanned) without any suspension.

Scanning logic 204 is further configured to control the sending of proberequests and receiving of probe responses from access points. Moreover,first transceiver 206 and second transceiver 210 are configured tosimultaneously provide respective first and second probe requests viarespective first and second channels in response to receipt of a scaninstruction from scanning logic 204. The first probe request isconfigured to discover first access point(s) that are available tocommunicate with parallel scanning device 200 via the first channel. Thesecond probe request is configured to discover second access point(s)that are available to communicate with parallel scanning device 200 viathe second channel. For example, a first probe request may be sent fromfirst transceiver 206 on a channel in the 2.4 GHz band, and a secondprobe request may be sent from second transceiver 210 on a channel inthe 5 GHz frequency band. In another example, a first probe request maybe sent on a first channel in a frequency band (e.g., 2.4 GHz or 5 GHz),and a second request may be sent on a second channel in the samefrequency band.

A probe request is a request (e.g., frame) that is configured to solicita response from each access point that is available to communicate withthe parallel scanning device (parallel scanning device 200) with whichthe probe request is transmitted. The probe request may requestinformation and/or contain information such as service set identifiers,supported rates, extended supported rates, distribution system parameterset, supported operating classes, high throughput capabilities, 20/40basic service set coexistence, extended capabilities, service setidentifier list, channel usage, interworking, a mesh identifier, and/orother information (e.g., vendor specific information).

Scanning logic 204 is configured to monitor the channels that are beingscanned by first transceiver 206 and second transceiver 210 for adesignated period of time after the probe requests are sent to determinewhether a response is received from one or more access points. Thedesignated period of time (a.k.a dwell time) is a configurable parameter(e.g., 20 milliseconds). An access point that is available tocommunicate with parallel scanning device 200 via the scanned channelmay respond to the probe request with a probe response (e.g., frame).The probe response may contain information such as timestamp, beaconinterval, capability, service set identifier, supported rates, frequencyhopping parameter set, distributed service set parameter set,contention-free parameter set, independent basic service set, country,frequency hopping parameters, frequency hopping pattern table, powerconstraint, channel switch announcement, extended supported rates,robust security network, basic service set load, beacon timing, and/orother information. The scanning operation may continue with the sendingof probe requests and receiving of probe responses via each of thechannels in sequential order (e.g., channel 1 is scanned before channel2).

There may be more channels to scan in the 5 GHz frequency band than inthe 2.4 GHz frequency band. Thus, in one example embodiment, after allchannels in the 2.4 GHz frequency band have been scanned during aparallel scanning process, both first transceiver 206 and secondtransceiver 210 may be used to scan the remaining channels in the 5 GHzfrequency band. In accordance with this example embodiment, the parallelscanning process involves simultaneously sending probe requests todifferent channels in the same frequency band (i.e., the 5 GHz frequencyband in this example). While there may be no interference problems whenfirst transceiver 206 and second transceiver 210 simultaneously operatein different frequency bands, there may be some interference issues withfirst transceiver 206 and second transceiver 210 operating in the samefrequency band. For example, there may be channel interference issues iftwo probe requests are sent to two channels that are adjacent to eachother. Thus, scanning logic 204 may be configured to determine theseparation needed between the channels to be scanned to avoidinterference issues. This determination may be based on the antennaconfiguration and/or specific characteristics of the frequency bands(e.g., channel width and/or spacing between the channels).

For example, scanning logic 204 may determine an isolation measurebetween first and second channels that are to be scanned. The isolationmeasure indicates an extent of isolation that exists between the firstand second channels. In accordance with this example, scanning logic 204may compare the isolation measure to a predetermined threshold. If theisolation measure is greater than the threshold, scanning logic 204 maydetermine that probe requests are to be sent via the first and secondchannels simultaneously. For instance, the isolation measure beinggreater than the threshold may indicate that there is sufficientseparation between the first and second channels for the probe requeststo be sent via the first and second channels simultaneously withoutcausing either probe request to interfere with the other. If theisolation measure is less than the threshold, scanning logic 204 maydetermine that probe requests are not to be sent via the first andsecond channels simultaneously. For instance, the isolation measurebeing less than the threshold may indicate that there is insufficientseparation between the first and second channels for the probe requeststo be to be sent via the first and second channels simultaneously.Nevertheless, one or more antennas may be tuned to the first and/orsecond channels to passively listen for beacons from access points.

Scanning logic 204 is further configured to provide scan results to anapplication. Such application may be a software-based application on asmartphone or other mobile parallel scanning devices. The scan resultsmay indicate access points that are available to communicate withparallel scanning device 200 via the scanned channels of one or morefrequency bands. In particular, the scan results may indicate eachaccess point that is available to connect with the parallel scanningdevice 200 via each scanned channel. The scan results may includeinformation (e.g., addresses, capabilities, and beacon times) compiledfrom probe responses received from available access points.

In embodiments, parallel scanning device 200 may operate in various waysto perform a parallel scanning operation. For instance, FIG. 3 depicts aflowchart 300 of an example method for parallel scanning in accordancewith an embodiment. Flowchart 300 is described with respect to parallelscanning device 200 and communication system 100 for illustrativepurposes. The steps of flowchart 300 may be performed in an orderdifferent than the order shown in FIG. 3 in some embodiments. Furtherstructural and operational embodiments will be apparent to personsskilled in the relevant art(s) based on the following description offlowchart 300.

Flowchart 300 begins with step 302. In step 302, a scan instructionindicating that a plurality of channels of a wireless network are to bescanned. For example, in an embodiment, scanning logic 204 is configuredto provide the scan instruction indicating that the plurality ofchannels (e.g., channels of the 2.4 GHz and/or 5 GHz frequency bands) ofthe wireless network (e.g., communication network 106) are to bescanned. The scan instruction may be generated by scanning logic 204 orderived from a scan request from an application (e.g., a softwareapplication running on a smartphone), a user command, or some othersource. The scan instruction may be provided to first transceiver 206and second transceiver 210 in the scanning process.

Flowchart 300 continues with step 304. In step 304, a scanning operationis initiated with regard to the plurality of channels in response toreceiving the scan instruction. The scanning operation includessimultaneously providing a first probe request via a first channel ofthe plurality of channels from a first transceiver of a parallelscanning device and a second probe request via a second channel of theplurality of channels from a second transceiver of the parallel scanningdevice in response to receiving the scan instruction. The first proberequest is configured to discover one or more first access points thatare available to connect with the parallel scanning device via the firstchannel. The second probe request is configured to discover one or moresecond access points that are available to connect with the parallelscanning device via the second channel.

For example, in an embodiment, scanning logic 204 is configured toinitiate a scanning operation as described above in connection withparallel scanning device 200. The scanning operation may includesimultaneously providing a first probe request via a first channel ofthe plurality of channels (e.g., channels on either the 2.4 GHz or the 5GHz frequency band) from first transceiver 206 of parallel scanningdevice 200 and a second probe request via a second channel of theplurality of channels from second transceiver 210 of parallel scanningdevice 200 in response to receiving the scan instruction from scanninglogic 204. The first probe request is configured to discover one or morefirst access points that are available to connect with parallel scanningdevice 200 via the first channel. Moreover, the second probe request isconfigured to discover one or more second access points that areavailable to connect with parallel scanning device 200 via the secondchannel.

In an embodiment, first transceiver 206 and second transceiver 210 areconfigured to simultaneously provide the first probe request via thefirst channel in a first wireless local area network frequency band(e.g., 2.4 GHz frequency band or 5 GHz frequency band) and the secondprobe request via the second channel in a second wireless local areanetwork frequency band that is different from the first wireless localarea network frequency band. In another embodiment, first transceiver206 and second transceiver 210 are configured to simultaneously providethe first and second probe requests via respective first and secondchannels of the same wireless local area network frequency band (e.g.,either 2.4 GHz or 5 GHz). In yet another example embodiment, firsttransceiver 206 and second transceiver 210 are configured tosimultaneously send the respective first and second probe requests froma single, shared antenna. In a further embodiment, first transceiver 206and second transceiver 210 are configured to simultaneously provide therespective first and second probe requests from respective first andsecond antennas.

In an example embodiment, scanning logic 204 is configured to monitorthe first channel during a designated period of time (e.g., dwell time)to determine whether at least one first response is received from atleast one respective first access point via the first channel inresponse to the first probe request. In accordance with this embodiment,scanning logic 204 is further configured to monitor the second channelduring the designated period of time to determine whether at least onesecond response is received from at least one respective second accesspoint via the second channel in response to the second probe request.The dwell time is configurable (e.g., 30 milliseconds) and may beconfigured manually or automatically by a user of the parallel scanningdevice 200, by a software program/routine, or some other entity.

In an example embodiment, scanning logic 204 is configured to providescan results regarding the scanning operation to an application (e.g.,an application on a mobile device). The scan results may indicate accesspoints that are available to communicate with parallel scanning device200 via the plurality of channels of the wireless network (e.g.,channels on the 2.4 GHz frequency band and/or the 5 GHz frequency band).In particular, the scan results may indicate each first access pointfrom which a first response is received and each second access pointfrom which a second response is received. The scan results may includeinformation (e.g., addresses, capabilities, and/or beacon times)gathered from probe responses received from the available access points.

FIG. 4 depicts a timing diagram of a parallel scanning technique inaccordance with an embodiment. FIG. 4 is described in connection withcommunication system 100 and/or parallel scanning device 200 forillustration purposes, and is not intended to be limiting. Timingintervals 402 correspond to a first frequency band (2.4 GHz in thisnon-limiting example), and timing intervals 404 correspond to a secondfrequency band (5.0 GHz in this non-limiting example). “A” represents afirst transceiver (e.g., first transceiver 206) in a dual-transceiverdevice (e.g., parallel scanning device 104), and “B” represents a secondtransceiver (e.g., second transceiver 210) in the dual-transceiverdevice). “CH 1” represents a first channel of the first frequency band;“CH 2” represents a second channel of the first frequency band; and “CH3” represents a third channel of the first frequency band. “CH 36”represents a first channel of the second frequency band; “CH 40”represents a second channel of the second frequency band; and “CH 44”represents a third channel of the second frequency band. “CH 11”represents a “home channel” with which each of the first and secondtransceivers A and B has an active connection (e.g., association). Itwill be recognized that Channel 11 (represented as “CH 11”) of the firstfrequency band is described as being the home channel for illustrativepurposes and is not intended to be limiting.

In the embodiment of FIG. 4, a parallel scanning device is configured tooperate in MIMO mode. At time t1, both transceivers A and B of theparallel scanning device are associated with home channel 11. Uponreceiving a scan request at time t2, transceiver A moves to channel 1(i.e., to scan for access points that are available on channel 1), andtransceiver B moves to channel 36 for scanning (i.e., to scan for accesspoints that are available on channel 36). At time t3, to continue thescanning operation, transceiver A moves to channel 2 (i.e., to scan foraccess points that are available on channel 2), and transceiver B movesto channel 40 (i.e., to scan for access points that are available onchannel 40). This scanning operation may continue until all desiredchannels are scanned. As mentioned above, at time t1, transceivers A andB are operating in MIMO mode for illustrative purposes. However, it willbe recognized that transceivers A and B need not necessarily operate inMIMO mode at t1. For instance, transceivers A and B may operate in RSDBmode (e.g., multiple MAC/PHY/radio chains for the multiple transceivers,with the chains being capable of operating in different channels/bands)in different channels; or one of the transceivers A or B may be idle att1; or both of the transceivers A and B may be idle at t1.

FIG. 5 is a block diagram of another example parallel scanning device500 in accordance with an embodiment. Parallel scanning device 500 maybe an example of any of the parallel scanning devices shown in FIG. 1(e.g., parallel scanning device 104). Parallel scanning device 500includes an application 502, a driver 504, memory 506, a host interface508, configuration registers 510, a transceivers 512 and 516 (denoted astransceiver A and transceiver B, respectively). Transceiver 512 andtransceiver 516 are shown in FIG. 5 as being associated with antenna 514and antenna 518, respectively. In embodiments, antenna 514 and antenna518 may be configured according to an antenna configuration in whichantenna 514 and antenna 518 are the same, in which antenna 514 andantenna 518 are different, in which antenna 514 and antenna 518 areincluded in an antenna array, or other suitable configuration. Inembodiments, parallel scanning device 500 may include other componentsnot shown in FIG. 5 or may include fewer components than shown in FIG.5. Similar to parallel scanning device 200, parallel scanning device 500is capable of operating in a variety of modes: SISO, MIMO, or RSDB. Theoperating modes, antenna configuration and any other configurationparameters regarding transceiver 512 and transceiver 516 may be storedin configuration registers 510 that are accessible by driver 504.

In an example embodiment, driver 504 receives a scan request 520 fromapplication 502. Application 502 may be any application (e.g., softwareprogram) that seeks information that can be determined from a scan ofthe channels in the frequency band(s) with which parallel scanningdevice 500 is compatible. Upon receipt of the scan request 520, driver504 generates parallel scan instructions 524 and 526 based on the scanrequest 520. Driver 504 provides the parallel scan instructions 524 and526 to transceiver 512 and transceiver 516, respectively. In an example,embodiment, driver 504 is a Wi-Fi driver. For instance, driver 504 maybe configured to provide configuration and management support such asenumerating, joining, and checking the status of available Wi-Finetworks, encryption services, etc. For example, driver 504 may emulatean Ethernet device and use the configuration and management utilitiesbuilt into the operation system or utilities from other sources (e.g.,vendors or manufacturers). Driver 504 is configured to accessconfiguration registers 510 to obtain and/or store configurationparameters for transceiver 512 and transceiver 516. Host interface 508enables driver 504 to interact with various other components of parallelscanning device 500.

Transceiver 512 and transceiver 516 are configured to receive parallelscan instructions 524 and 526 from driver 504 and to perform a parallelscanning operation accordingly. The parallel scanning operation mayinclude an active scan and/or a passive scan by each of transceiver 512and transceiver 516. An active scan involves the generation of proberequest frames and subsequent processing of received probe responseframes. For example, transceiver 512 may actively send a probe requestframe on channel 1 of the 2.4 GHz frequency band and receives a proberesponse frame from an access point that is available on channel one. Apassive scan involves the broadcast of beacons from available accesspoints in a designated channel and subsequent processing of receivedbeacons. For example, transceiver 516 may passively listen for a beaconfrom an access point on channel 36 of the 5 GHz frequency band. Scanresults from both transceiver 512 and transceiver 516 are collected bydriver 504 and provided to application 502 for further processing. Scanresults may include information about access points (e.g., identifiers,capabilities, etc.) discovered during the parallel scan operation in the2.4 GHz frequency band and/or the 5 GHz frequency band.

Application 502 may utilize the scan results to form decisions regardingthe available access points and/or communication network. For example,application 502 may decide to begin the association process with one ofthe access points discovered during the scanning operation.

In embodiments, parallel scanning device 200 or parallel scanning device500 may operate in various ways to perform a scanning operation usingthe included first and second transceivers. For instances, FIG. 6depicts a flowchart 600 of an example method for scanning a plurality ofchannels in a wireless network frequency band in accordance with anembodiment. In accordance with the embodiment of FIG. 6, twotransceivers, each having a dedicated antenna, are used to scan onefrequency band to leverage channel switching time. Flowchart 600 isdescribed with respect to parallel scanning device 200 and parallelscanning device 500 for illustrative purposes. The steps of flowchart600 may be performed in an order different than shown in FIG. 6 in someembodiments. Further structural and operational embodiments will beapparent to persons skilled in the relevant art(s) based on thefollowing description of flowchart 600 and parallel scanning device 500.

Flowchart 600 begins with step 602. In step 602, the first transceiver,which is associated with a first access point that is configured tocommunicate via a first channel, receives an indication that the secondtransceiver is to provide a probe request via a second channel that isadjacent to the first channel. The probe request is configured todiscover one or more second access points that are available to connectwith the parallel scanning device via the second channel.

For example, in an embodiment, transceiver 512 may be associated with anaccess point on channel 36 of the 5 GHz frequency band. Transceiver 512may receive an indication from driver 504 and/or transceiver 516 thattransceiver 516 is to transmit a probe request via channel 40 of thesame frequency band (i.e., the 5 GHz frequency band in this example).For instance, channel 40 may be adjacent to channel 36.

In accordance with this example, while transceiver 516 prepares to scanchannel 40 (e.g., preparing the probe request, issuing a channel switchrequest, etc.), transceiver 512 may facilitate the scanning operation bytransmitting designated frames to the associated access point. Forinstance, transceiver 512 may send a message to the associated accesspoint, requesting that the first access point suspend communication withthe parallel scanning device 500 for a period of time. In particular,transceiver 512 may be configured to send a frame (e.g., CTS2Self) toprotect data that will be sent from parallel scanning device 500. Such aframe may include information such as receiver address, time duration,and a frame check sequence. Additionally or alternatively, transceiver512 may initiate a successful frame exchange (e.g., Announce PM=1) withthe associated access point in order to change power management modes.The power management modes may include but are not limited to an activemode (AM), during which parallel scanning device 500 is awake and mayreceive a frame at any time, and a power save (PS) mode, during whichparallel scanning device 500 listens for beacons and sends PS-pollframes to the associated access point without transmitting or receivingnormal data to and from the associated access point. Once the necessaryframes (e.g., channel switch request, power management request, data/ACKrequest) have been transmitted to the associated access point, flowchart600 proceeds to the next step.

In step 604, the first transceiver is turned off in response toreceiving the indication. For example, in the embodiment describedabove, transceiver 512 is turned off (e.g., powered down or switched toidle mode) in response to receiving the indication that transceiver 516is to provide a probe request via channel 40, which is adjacent tochannel 36 in the 5 GHz frequency band, and further in response to thetransmittal of the necessary frames to prepare transceiver 516 to scanchannel 40.

With transceiver 512 being off, there is no risk of transceiver 512causing channel interference with respect to transceiver 516 iftransceiver 516 is turned on. Accordingly, transceiver 516 may be turnedon to initiate a scanning operation. During the scanning operation,transceiver 516 may provide the probe request via channel 40, and driver504 may monitor channel 40 during a designated period of time (e.g.,dwell time) to determine whether at least one response is received fromat least one second access point.

After the dwell time, as transceiver 516 prepares to scan the nextchannel, transceiver 512 may be turned on to resume normalfunctionality. In particular, transceiver 512 may be turned on toreceive a beacon from the first, associated access point whiletransceiver 516 is preparing to provide a second probe request via athird channel, which is different from the first channel and the secondchannel. The second probe request is configured to discover one or morethird access points that are available to connect with the parallelscanning device via the third channel. For example, transceiver 512 maybe turned on as transceiver 516 is preparing to provide the second proberequest via channel 44 in the 5 GHz frequency band.

The disclosed technologies may be embodied in hardware, and/or acombination of hardware, software and/or firmware implementations otherthan those described herein. Any software, hardware, and firmwareimplementations suitable for performing the functions described hereincan be used.

C. Examples Illustrating Scanning Times

The parallel scanning process can reduce the time required to scan allthe channels in one or more frequency bands. For example, the total scantime may be computed as a product of the number of channels to bescanned and the dwell time, which is a configurable parameter. If thedwell time is designated to be 20 milliseconds (ms) and there are 11available channels in the 2.4 GHz frequency band, it would take 220 msto complete the scan of the 2.4 GHz frequency band. There are far morechannels in the 5 GHz frequency band than in the 2.4 GHz frequency band.Thus, according to the above example, the scan of the 2.4 GHz frequencyband may be completed before that the scan of the 5 GHz frequency band.Using a parallel scanning technique described herein, the total scantime of both the 2.4 GHz frequency band and the 5 GHz frequency band maybe reduced by at least 220 ms.

Such parallel scanning technique can substantially reduce the scanningtime as compared to sequential scanning techniques. For example, assumethere are 14 channels in the 2.4 GHz frequency band and 29 channels, ofwhich 13 are dynamic frequency selection (DFS) channels, in the 5 GHzfrequency band. DFS channels are regulated as mandatory passive scanchannels. Thus, for the passive scan channels, the dwell time may be setat 110 ms, and for the active scan channels, the dwell time may be setat 20 ms. The scan time for both the 2 GHz frequency band and the 5 GHzfrequency band according to the sequential scanning technique may becalculated as:

2 GHz active scan time+5 GHz active scan time+5 GHz passive scantime=(14×20)+(29−13)×20+13×110)=2030 ms (or approximately 2 seconds)

In contrast, the scan time for both the 2 GHz frequency band and the 5GHz frequency band according to the parallel scanning technique may becalculated as:

MAX(2 GHz active scan time, 5 GHz active scan time)+0.5×(5 GHz passivescan time)=MAX(280,320)+1430/2=1035 ms (or approximately 1 second).

D. Example Computing System Implementation

The embodiments described herein, including systems, methods/processes,and/or apparatus, may be implemented using well known computing devices,such as computer 700 shown in FIG. 7. For example, parallel scanningdevice 104 depicted in FIG. 1; elements of parallel scanning device 200including scanning logic 204 depicted in FIG. 2; elements of parallelscanning device 500 including driver 504 depicted in FIG. 5; each of thesteps of flowchart 300 depicted in FIG. 3; and each of the steps offlowchart 600 depicted in FIG. 6 can each be implemented using one ormore computers 700.

As shown in FIG. 7, computer 700 includes a processing unit 706.Processing unit 706 may comprise one or more processors (also calledcentral processing units or CPUs) or processor cores. Processing unit706 is connected to a communication infrastructure 702, such as acommunication bus. Computer 700 also includes a primary or main memory708, such as random access memory (RAM). Main memory 708 has storedtherein control logic 724 (computer software), and data.

Computer 700 also includes one or more secondary storage devices 710.Secondary storage devices 710 include, for example, a hard disk drive712 and/or a removable storage device or drive 714, as well as othertypes of storage devices, such as memory cards and memory sticks. Forinstance, computer 700 may include an industry standard interface, suchas a universal serial bus (USB) interface for interfacing with devicessuch as a memory stick. Removable storage drive 714 represents a floppydisk drive, a magnetic tape drive, a compact disk drive, an opticalstorage device, tape backup, etc.

Removable storage drive 714 interacts with a removable storage unit 716.Removable storage unit 716 includes a computer useable or readablestorage medium 718 having stored therein computer software 726 (controllogic) and/or data. Removable storage unit 1216 represents a floppydisk, magnetic tape, compact disc (CD), digital versatile disc (DVD),Blu-ray disc, optical storage disk, memory stick, memory card, or anyother computer data storage device. Removable storage drive 714 readsfrom and/or writes to removable storage unit 716 in a well-known manner.

Computer 700 also includes input/output/display devices 704, such asmonitors, keyboards, pointing devices, etc.

Computer 700 further includes a communication or network interface 720.Communication interface 720 enables computer 700 to communicate withremote devices. For example, communication interface 720 allows computer700 to communicate over communication networks or mediums 722(representing a form of a computer useable or readable medium), such aslocal area networks (LANs), wide area networks (WANs), the Internet,etc. Network interface 720 may interface with remote sites or networksvia wired or wireless connections. Examples of communication interface722 include but are not limited to a modem (e.g., for 3G and/or 4 Gcommunication(s)), a network interface card (e.g., an Ethernet card forWi-Fi and/or other protocols), a communication port, a Personal ComputerMemory Card International Association (PCMCIA) card, a wired or wirelessUSB port, etc.

Control logic 728 may be transmitted to and from computer 700 via thecommunication medium 722.

Any apparatus or manufacture comprising a computer useable or readablemedium having control logic (software) stored therein is referred toherein as a computer program product or program storage device. Thisincludes, but is not limited to, computer 700, main memory 708,secondary storage devices 710, and removable storage unit 716. Suchcomputer program products, having control logic stored therein, may beexecuted by processing unit 706 to perform methods described herein. Forexample, such computer program products, when executed by processingunit 706, may cause processing unit 706 to perform any of the steps offlowchart 300 of FIG. 3 and flowchart 600 of FIG. 6. The disclosedtechnologies may be embodied in software, hardware, and/or firmwareimplementations other than those described herein. Any software,hardware, and firmware implementations suitable for performing thefunctions described herein can be used.

E. Conclusion

While various embodiments have been described above, it should beunderstood that they have been presented by way of example only, and notlimitation. It will be apparent to persons skilled in the relevant artthat various changes in form and detail can be made therein withoutdeparting from the spirit and scope of the embodiments. Thus, thebreadth and scope of the embodiments should not be limited by any of theabove-described exemplary embodiments, but should be defined only inaccordance with the following claims and their equivalents.

What is claimed is:
 1. A method comprising: receiving a scan instructionindicating that a plurality of channels of a wireless network are to bescanned; and initiating a scanning operation with regard to theplurality of channels in response to receiving the scan instruction, thescanning operation comprising: simultaneously providing a first proberequest via a first channel of the plurality of channels from a firsttransceiver of a parallel scanning device and a second probe request viaa second channel of the plurality of channels from a second transceiverof the parallel scanning device in response to receiving the scaninstruction, the first probe request configured to discover one or morefirst access points that are available to connect with the parallelscanning device via the first channel, the second probe requestconfigured to discover one or more second access points that areavailable to connect with the parallel scanning device via the secondchannel.
 2. The method of claim 1, wherein simultaneously providing thefirst probe request and the second probe request comprises:simultaneously providing the first probe request via the first channelin a first wireless local area network frequency band and the secondprobe request via the second channel in a second wireless local areanetwork frequency band that is different from the first wireless localarea network frequency band.
 3. The method of claim 1, whereinsimultaneously providing the first probe request and the second proberequest comprises: simultaneously providing the first probe request viathe first channel and the second probe request via the second channel ina same wireless local area network frequency band.
 4. The method ofclaim 1, wherein simultaneously providing the first probe request andthe second probe request comprises: simultaneously providing the firstprobe request via the first channel and the second probe request via thesecond channel in a 5 gigahertz wireless local area network frequencyband.
 5. The method of claim 1, wherein simultaneously providing thefirst probe request and the second probe request comprises:simultaneously providing the first probe request and the second proberequest from a single antenna.
 6. The method of claim 1, whereinsimultaneously providing the first probe request and the second proberequest comprises: simultaneously providing the first probe request froma first antenna and the second probe request from a second antenna thatis different from the first antenna.
 7. The method of claim 1, whereinthe scanning operation further comprises: monitoring the first channelduring a designated period of time to determine whether at least onefirst response is received from at least one respective first accesspoint via the first channel in response to the first probe request; andmonitoring the second channel during the designated period of time todetermine whether at least one second response is received from at leastone respective second access point via the second channel in response tothe second probe request.
 8. The method of claim 1, further comprisingproviding scan results regarding the scanning operation to anapplication, the scan results indicating each first access point fromwhich a first response is received and each second access point fromwhich a second response is received.
 9. A parallel scanning devicecomprising: scanning logic configured to provide a scan instructionindicating that a plurality of channels of a wireless network are to bescanned; and first and second transceivers configured to simultaneouslyprovide respective first and second probe requests via respective firstand second channels of the plurality of channels in response to receiptof the scan instruction, the first probe request configured to discoverone or more first access points that are available to connect with theparallel scanning device via the first channel, the second probe requestconfigured to discover one or more second access points that areavailable to connect with the parallel scanning device via the secondchannel.
 10. The parallel scanning device of claim 9, wherein the firstchannel is in a first wireless local area network frequency band and thesecond channel is in a second wireless local area network frequency bandthat is different from the first wireless local area network frequencyband.
 11. The parallel scanning device of claim 9, wherein the firstchannel and the second channel are in a same wireless local area networkfrequency band.
 12. The parallel scanning device of claim 9, wherein thefirst channel and the second channel are in a 5 gigahertz wireless localarea network frequency band.
 13. The parallel scanning device of claim9, wherein the first and second transceivers are configured tosimultaneously provide the respective first and second probe requestsfrom a single antenna.
 14. The parallel scanning device of claim 9,wherein the first and second transceivers are configured tosimultaneously provide the respective first and second probe requestsfrom respective first and second antennas.
 15. The parallel scanningdevice of claim 9, wherein the scanning logic is further configured tomonitor the first channel during a designated period of time todetermine whether at least one first response is received from at leastone respective first access point via the first channel in response tothe first probe request, and wherein the scanning logic is furtherconfigured to monitor the second channel during the designated period oftime to determine whether at least one second response is received fromat least one respective second access point via the second channel inresponse to the second probe request.
 16. The parallel scanning deviceof claim 9, wherein the scanning logic is further configured to providescan results to an application, the scan results indicating each firstaccess point that is available to connect with the parallel scanningdevice via the first channel and each second access point that isavailable to connect with the parallel scanning device via the secondchannel.
 17. The parallel scanning device of claim 9, wherein thescanning logic is further configured to determine an isolation measurebetween the first and second channels, the isolation measure indicatingan extent of isolation that exists between the first and secondchannels.
 18. In a parallel scanning device that includes a firsttransceiver and a second transceiver, a method comprising: receiving anindication at the first transceiver, which is associated with a firstaccess point that is configured to communicate via a first channel, thatthe second transceiver is to provide a probe request via a secondchannel that is adjacent to the first channel, the probe requestconfigured to discover one or more second access points that areavailable to connect with the parallel scanning device via the secondchannel; and turning off the first transceiver in response to receivingthe indication.
 19. The method of claim 18, further comprising: turningon the second transceiver to initiate a scanning operation thatcomprises providing the probe request via the second channel from thesecond transceiver, and monitoring the second channel during the periodof time to determine whether at least one response is received from atleast one second access point.
 20. The method of claim 18, furthercomprising: turning on the first transceiver to receive a beacon fromthe first access point while the second transceiver is preparing toprovide a second probe request via a third channel that is differentfrom the first channel and the second channel; wherein the second proberequest is configured to discover one or more third access points thatare available to connect with the parallel scanning device via the thirdchannel.